import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

public class Server {
    private ServerSocket serverSocket;
    private List<PrintWriter> allOut = new ArrayList<>();
    public Server(){
        try{
            System.out.println("Starting server...");
            serverSocket = new ServerSocket(8088);
            System.out.println("server start complete!");
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    public void start(){
        try{
            while(true) {
                System.out.println("Waiting for client link...");
                Socket socket = serverSocket.accept();
                System.out.println("a client linked");
                ClientHandler handler = new ClientHandler(socket);
                Thread t = new Thread(handler);
                t.start();
            }
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Server server = new Server();
        server.start();
    }

    private class ClientHandler implements Runnable{
        private Socket socket;
        private String host;
        public ClientHandler(Socket socket){
            this.socket = socket;
            host = socket.getInetAddress().getHostAddress();
        }
        public void run(){
            PrintWriter pw = null;
            try{
                InputStream in = socket.getInputStream();
                InputStreamReader isr = new InputStreamReader(in,"UTF-8");
                BufferedReader br = new BufferedReader(isr);

                OutputStream out = socket.getOutputStream();
                OutputStreamWriter osw = new OutputStreamWriter(out, StandardCharsets.UTF_8);
                BufferedWriter bw = new BufferedWriter(osw);
                pw = new PrintWriter(bw,true);

                synchronized (allOut){
                    allOut.add(pw);
                }

                sendMessage(host + "is online, current number of people online:" + allOut.size());

                String line;
                while ((line = br.readLine()) != null) {
                    sendMessage(host + "say:" + line);
                }
            }catch(IOException e){
                e.printStackTrace();
            }finally{
                synchronized (allOut) {
                    allOut.remove(pw);
                }
                System.out.println(host+"is offline, current number of people online:"+allOut.size());
            }
        }
        private void sendMessage(String line){
            System.out.println(line);
            synchronized (allOut) {
                for (PrintWriter o : allOut) {
                    o.println(line);
                }
            }
        }
    }
}